With Sonnet 140, William Shakespeare at first seems to set out on some general counsel for his mistress not to try his patience too much, as doing so might drive him mad and cause him, in his madness, to say bad things about her. The damage this could do would be exacerbated by a world that is itself full of mad people who would be inclined to believe him even if what he came out with were but scurrilous lies.

Strongly implied also though is that not everything scandalous he might say about his mistress would necessarily be untrue, And with the last line of the closing couplet, he then ties his sonnet firmly back to the previous one and reiterates his request that even though she obviously has other lovers, she keep her eyes on him when they are together at least.

With Sonnet 139, William Shakespeare finds himself quite comfortably in the domain of the classical Petrarchan sonnet, invoking the themes and poetic tropes that other sonneteers of the period, most notably Sir Philip Sidney in his Astrophel and Stella use to speak about their mistress's capacity to captivate and, if they so wish, kill them with their looks.

The initial plea with the mistress is simple and straightforward: I know you have other men, so when you are with me, just tell me to my face that this is the case, rather than flirting with them with furtive glances. Having devoted the octave – the eight lines of the first two quatrains – of his sonnet to this principal argument, he then uses the sestet – the six lines of the final quatrain and the closing couplet – to propose a somewhat sophistic excuse for his mistress's behaviour, allowing for the fanciful idea that she divert her devastating looks to other men so as to spare him additional suffering, which, he finally resolves she shouldn't do, since he'd rather 'die' – at least metaphorically – than be left in limbo...

With Sonnet 138 William Shakespeare takes a step back and reflects on how both he and his mistress in their relationship with each other are effectively living a lie which they both actively conspire to maintain: she pretends to be faithful to him although she fully knows that he knows that she obviously isn't, and he goes along with it when she treats him as if he were an innocent young lover who not only is still in his prime but who is also uneducated in matters of love, both of which she similarly knows not to be the case.